async signURL()

in src/sigv4/DefaultSigV4.ts [62:171]
95 lines of code
6 McCabe index (conditional complexity)

  async signURL(
    method: string,
    scheme: string,
    serviceName: string,
    hostname: string,
    path: string,
    payload: string,
    queryParams: Map<string, string[]> | null
  ): Promise<string> {
    const now = this.getDateTimeString();
    const today = this.getDateString(now);

    const algorithm = 'AWS4-HMAC-SHA256';
    let region = '';
    // in AWS SDK v3 region is a function
    if (this.chimeClient.config.region instanceof Function) {
      region = await this.chimeClient.config.region();
    } else {
      region = this.chimeClient.config.region;
    }

    const signedHeaders = 'host';

    const canonicalHeaders = 'host:' + hostname.toLowerCase() + '\n';
    const credentialScope = today + '/' + region + '/' + serviceName + '/' + 'aws4_request';
    let credentials = undefined;
    // in AWS SDK v3 credentials is a function
    if (this.chimeClient.config.credentials instanceof Function) {
      credentials = await this.chimeClient.config.credentials();
    } else {
      credentials = this.chimeClient.config.credentials;
    }

    let params: Map<string, string[]> = new Map<string, string[]>();
    params.set('X-Amz-Algorithm', [algorithm]);
    params.set('X-Amz-Credential', [
      encodeURIComponent(credentials.accessKeyId + '/' + credentialScope),
    ]);
    params.set('X-Amz-Date', [now]);
    params.set('X-Amz-Expires', ['10']);
    params.set('X-Amz-SignedHeaders', ['host']);
    if (credentials.sessionToken) {
      params.set('X-Amz-Security-Token', [encodeURIComponent(credentials.sessionToken)]);
    }
    params.set(Versioning.X_AMZN_VERSION, [encodeURIComponent(Versioning.sdkVersion)]);
    params.set(Versioning.X_AMZN_USER_AGENT, [
      encodeURIComponent(Versioning.sdkUserAgentLowResolution),
    ]);

    queryParams?.forEach((values: string[], key: string) => {
      const encodedKey = encodeURIComponent(key);
      values.sort().forEach((value: string) => {
        if (!params.has(encodedKey)) {
          params.set(encodedKey, []);
        }
        params.get(encodedKey).push(encodeURIComponent(value));
      });
    });

    let canonicalQuerystring = '';
    params = new Map([...params.entries()].sort());
    params.forEach((values: string[], key: string) => {
      values.forEach(value => {
        if (canonicalQuerystring.length) {
          canonicalQuerystring += '&';
        }
        canonicalQuerystring += key + '=' + value;
      });
    });

    const canonicalRequest =
      method +
      '\n' +
      path +
      '\n' +
      canonicalQuerystring +
      '\n' +
      canonicalHeaders +
      '\n' +
      signedHeaders +
      '\n' +
      toHex(await this.hmac(payload));

    const hashedCanonicalRequest = toHex(await this.hmac(canonicalRequest));

    const stringToSign =
      'AWS4-HMAC-SHA256\n' +
      now +
      '\n' +
      today +
      '/' +
      region +
      '/' +
      serviceName +
      '/aws4_request\n' +
      hashedCanonicalRequest;

    const signingKey = await this.getSignatureKey(
      credentials.secretAccessKey,
      today,
      region,
      serviceName
    );

    const signature = toHex(await this.hmac(stringToSign, signingKey));

    const finalParams = canonicalQuerystring + '&X-Amz-Signature=' + signature;

    return scheme + '://' + hostname + path + '?' + finalParams;
  }